The present invention relates, in general, to moisture monitoring dryer control apparatus, and, more particularly, to moisture control apparatus for use with many standard forms of commercial, institutional, industrial and domestic tumbler dryers for terminating the drying cycle when the residual moisture in the goods being dried reaches a desired level and initiating a cool-down cycle to deliver the goods at near room temperature conditions.
Heretofore, various types of dryer control apparatus have been developed, involving some kind of moisture sensing device which undergoes change in its electrical properties in some relationship to moisture present in the air being monitored, to determine when clothes being dried in a tumbler dryer have reached a pre-determined state of dryness, providing electrical or electronic circuitry to turn off the dryer heater when the pre-determined dryer condition has been reached and allow the dryer to continue operating to cool the clothes before stopping the ventilating and tumbling operation. Some of such devices rely upon change in leakage of voltage across the sensor device at a rate dependent on the moisture content of the clothes, and some involve changes in electrical resistance path bearing a relationship to the moisture.
The present invention is designed to provide moisture monitoring apparatus for commercial, institutional, industrial and domestic tumbler dryers and the like having an improved humidity sensor of rugged and reliable construction capable of sustained operation in high-temperature dryers without degradation in overall system performance, wherein control circuitry is provided for terminating the drying cycle when the residual moisture of the goods being dried reaches the desired level and initiate cool-down cycle to deliver the goods at near room temperature, and which includes adjustment means for conveniently presetting the desired degree of dryness to be attained.
Another object of the present invention is to provide moisture monitoring and dryer control apparatus having visual display means in an LED bargraph display, to enable the operator to observe the progress of the drying cycle and optimize dryer loads.
A still-further object of the present invention is to provide a moisture monitoring and dryer control apparatus as described in the preceding paragraph, including sensing means for verification of dryer run status and control means for automatic termination of the drying cycle and initiation of the cool-down cycle.
Other objects, advantages and capabilities will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.